1. Field of the Invention
The present invention relates to the field of apparatus for ophthalmic surgery. More particularly, the present invention relates to the field of apparatus for cataract surgery.
2. Description of the Prior Art
In many types of ophthalmic surgery, it is often necessary to incise the anterior lens capsule of the crystalline lens of an eye to provide an opening on the anterior lens capsule so that the cataractous opaque lens can be removed. However, the anterior lens capsule of the eye is shielded by the corneal tissue. Therefore, before any cataract surgical apparatus can reach the anterior lens capsule of the eye, a passage wound has to be cut in the corneal tissue. After the cataract surgery, the corneal wound is closed with sutures.
The following prior art patents are found to be related to the field of surgical apparatus used in cataract surgeries.
1. U.S. Pat. No. 4,959,070 issued to McDonald on Sep. 25, 1990 for "Intraocular Lens Implantation" (hereafter referred to as the "McDonald Patent"). PA1 2. U.S. Pat. No. 4,844,065 issued to Faulkner on Jul. 4, 1989 for "Intraocular Lens Inserting Tool And Methods" (hereafter referred to as the "Faulkner Patent"). PA1 3. U.S. Pat. No. 4,785,810 issued to Baccala et al. on Nov. 22, 1988 for "Intraocular Lens Folding And Insertion Apparatus" (hereafter referred to as the "Baccala Patent"). PA1 4. U.S. Pat. No. 4,766,897 issued to Smirmaul on Aug. 30, 1988 for "Cataract Surgical Instrument" (hereafter referred to as the "Smirmaul Patent").
The Smirmaul Patent discloses an anterior lens capsule incising apparatus 10 for cutting an incision on the anterior capsule of the crystalline lens of an eye. The Smirmaul Patent incising apparatus 10 has a forward portion and a rearward portion interconnected by an elongated hollow shank 16, where the forward portion includes a circular blade holder 18, and the rearward portion includes a squeezable handle 12. There is a circular cutting blade 20 rotatably mounted within the circular blade holder 18 and attached to an elongated flexible wire 24, which in turn is disposed in the elongated hollow shank 16 and connected to the squeezable handle 12. When the handle 12 is squeezed, the flexible wire 24 will be stretched, which in turn will rotate the circular cutting blade 20. During cataract surgery, the forward portion of the incising instrument 10 is inserted through a passage wound cut on the corneal tissue of an eye, such that the circular blade holder 18 is disposed above the anterior lens capsule of the eye. When the handle 12 is squeezed, the rotatable cutting blade 20 cuts a circular incision on the anterior lens capsule of the eye for further intraocular surgery.
The Baccala Patent discloses an intraocular lens implanting apparatus 10 for inserting an artificial intraocular lens into the lens capsule of an eye, after an incision is cut on the anterior lens capsule and the natural intraocular lens is removed. The Baccala Patent implanting apparatus 10 has two elongated forceps arms 34 and 42. The front tip 16 of the first elongated forceps arm 34 has a concave surface 20, and the front tip 18 of the second elongated forceps arm 42 has a convex surface 22. An artificial intraocular lens can be folded between the concave surface 20 of the front tip 16 of the first elongated forceps arm 34 and the convex surface 22 of the front tip 18 of the second elongated forceps arm 42, and introduced into the lens capsule of an eye through the incision on the anterior lens capsule of the eye.
The Faulkner Patent also discloses an intraocular lens implanting apparatus 10. The Faulkner Patent implanting apparatus 10 has two elongated forceps arms 11 and 12. The front tips of the two elongated forceps arms 11 and 12 form jaws 13 for folding and holding an artificial intraocular lens. As shown in FIG. 8, when the jaws 13 are opened in the anterior chamber of an eye to release the artificial intraocular lens, the bent portion 27 of the two elongated forceps arms 11 and 12 are opened accordingly. Since the bent portion 27 is located within the wound cut on the corneal tissue, a relatively wide wound is required for allowing the bent portion 27 to expand.
The McDonald Patent again discloses an intraocular lens implanting apparatus 21. The McDonald Patent implanting apparatus 21 has two elongated forceps arms 22a and 23a crossing over each other and hingeably attached at point 24. When the front tips 22c and 23c are opened inside the anterior chamber, the hinge point 24 is located at the wound cut on the corneal tissue. Since the width of the hinge point 24 is fixed, the wound on the corneal tissue can be relatively narrow.
In the above four prior art patents, three of them, the Baccala Patent, the Faulkner Patent and the McDonald Patent, are not anterior lens capsule incising apparatus, but rather intraocular lens implanting apparatus. An anterior lens capsule incising apparatus is used in cataract surgery for cutting an incision on the anterior lens capsule of an eye, so that the natural lens of the eye can be removed and an artificial intraocular lens can be implanted therein. Alternatively, an intraocular lens implanting apparatus is used in the cataract surgery for inserting the artificial intraocular lens into the lens capsule of the eye, after the incision is cut on the anterior lens capsule of the eye and the natural intraocular lens of the eye is removed. The Baccala Patent, the Faulkner Patent and the McDonald Patent apparatus are more like a forceps apparatus, and none of them contain cutting blades for performing the function of cutting the incision on the anterior lens capsule of the eye.
The Smirmaul Patent apparatus 10 is an anterior lens capsule incising apparatus. Its forward portion, including the circular lens holder 18, can be inserted through a passage wound cut on the corneoscleral tissue of an eye, and disposed above the anterior lens capsule of the eye, so that its rotatable cutting blade 20 can cut a circular incision on the anterior lens capsule. The disadvantage of the Smirmaul Patent incising apparatus 10 is that it requires a wide passage wound cut on the corneoscleral tissue. The diameter of the rotatable circular cutting blade 20 of the Smirmaul Patent incising apparatus 10 is about six millimeters (6mm) (Column 3, line 23), which is the necessary size for cutting an adequate incision on the anterior lens capsule for further surgeries. Therefore the overall diameter of the circular blade holder is at least above seven millimeters (7mm). This requires that the width of the passage wound cut on the corneoscleral tissue to be not less than seven millimeters (7mm), which is wide by eye surgery standards. It is desirable to have the width of the passage wound cut on the corneoscleral tissue as narrow as possible, since a wider wound requires more surgical closing procedures and increases the period of convalescence.
Therefore, it is desirable to have an anterior lens capsule incising apparatus which can cut an adequate sized incision on the anterior lens capsule of an eye, but can also pass through a relatively narrow wound cut on the corneoscleral tissue of the eye.